1. Field of the Invention
The present invention relates to a deformable compression ring for use in a coaxial cable connector.
2. Prior Art
The plethora of compression-type coaxial connectors in current use all have limitations with regard to accepting a restricted size range of cables and can only be used once. Some connectors have the ability to exchange parts to adjust for out-of-size cables. The present art designs are one-time use. Due to the expense of many gold plated and specialty connectors now used in home theater and wireless and industrial applications, re-useability is a desirable feature when an error is made during installation.
Burris, in U.S. Pat. No. 5,525,076, discloses a compression-type coaxial cable connector including an outer tubular member having an axial bore for receiving a coaxial cable, a free end, and an inner end. A coupling member is attached to the inner end of the outer tubular member for coupling the coaxial cable to a mating coaxial cable connector. A securement means is carried by the outer tubular member for providing mechanical, and sealing engagement with the coaxial cable in response to a longitudinal compressive force. The operability of the securement means relies upon the compression of the outer shell to deform a groove to protrude inwardly thus securing a coaxial cable between the inward protrusion and a center post. In operation, the connector disclosed in the '076 patent has problems.
The aforesaid '076 patent teaches the use of a groove in the outer shell that, when compressed longitudinally, results in an inward deformation of the groove forming a 360 degree reduced diameter seal over the coaxial cable jacket. U.S. Pat. No. 6,042,422 further enhances the method by using a unique groove design. Burris has the difficulty of manufacture in that the groove needs to be made to a high tolerance to insure uniform compression, and the entire body (which is made from metal) needs to be annealed to effect compression at the groove/weakened location. The compression element (i.e., the groove) needs to be machined into the thick metal comprising the body of the connector. Another limitation is that upon compression of the body, it must be compressed evenly or the connector will not close properly. The connector disclosed in the '076 patent has the problem of manufacturing precision grooves and consistent metal annealing to allow the longitudinally-moving shell to produce equal circumferenced inward protrusions. If the heat treating is not perfect, too much force will be required to compress the outer shell of the connector thus making it difficult to use. In addition, keeping the correct groove shape to have the protrusions move inwardly (versus collapse) is difficult. U.S. Pat. No. 6,042,422 acknowledges this problem and discloses a securement member that optimizes the metal shape of this groove.
The second problem with the compression-type connector disclosed in U.S. Pat. No. 5,525,076 is that the compression tools used to compress the securement member do not apply longitudinal force equally over the 360 degrees of the rear compression shell. For example, the compression tool may only apply a compressive force on 270 degrees. In such an event, the securement member may not collapse equally, resulting in only partial radial inward deformation. This effect is dependent upon the compression tool used and the craft skills of the user. It would be desirable to provide an improved securement member that will provide uniform compression of a cable around the circumference thereof.
Holland, in U.S. Pat. No. 7,008,263, teaches of an internal compression ring that is removable and replaceable to meet a new demand in the market. The limitation on the Holland design, where the ring is deformed in the rear only by a rear tapered shell ID, is that this bigger taper that is needed to compress the ring also restricts the maximum OD cable that may be used.
Montena teaches of an outer shell/fastener moving from an open/outer position to a closed one resulting in the sloping ID of the shell compressing the body radially inward at its rear. This has the limitations of having to also heat treat the entire body to effect a soft compression of the trailing edge. It is also being limited as a one-use, connector.
Sterling, in U.S. Pat. No. 6,848,939, uses a wedge plug that compresses the cable between the body and ferrule and is located remotely from under the body/
Burris, in U.S. Pat. No. 7,018,235, also begins with a compression ring remote from the body but differs from Sterling in that this ring's final position is over the center tube/ferrule rear end and exerts radial force for holding and sealing by forming an arc. This arc is formed by the longitudinal force and the chamfer on both the rear edge of the body and the front inside edge of the shell/fastener. The limitations of this design is that the force is very dependant upon the material of the ring being able to form an arc shape rather than assume the method of the Sterling. This material must be restricted in type.
Chee, in U.S. Pat. No. 6,817,897, uses an inner ring that is fixed and requires a series of shoulders that bend inward as a group to effect compression. This compression is effected by the rear taper of the fastener's inner surface as it moves laterally.
Most prior art connectors that employ removable compression rings require that at least a portion of the axial bore of the body portion or the shell (and/or the outer surface of the compression ring) be conically tapered to effect radial deformation of the compression ring during longitudinal compression of the connector. The present invention, by using a perpendicular edge (shoulder) on the ID of the axial bore of the shell to longitudinally compress the compression ring, enables a cable having a larger OD to be inserted into the axial bore of the compression ring. By moving the grooved compression ring to a position within the axial lumen of the outer shell, as in the present invention, the outer shell and the body acts as a guide to insure radially uniform inward deformation of the mid-portion of the ring and allows the use of different materials than the body or shell for making the rings. Rubber, plastic, or specially spiked surfaces can be used for such cables with hard jackets for burial or plenum cables adapted for use in potential fire areas.